Wednesday, January 28, 2009

Interracial fertility: Over at 2blowhards, Gregory Cochran said in Monday's interview that:

Well, one usual claim is that individuals from every human population are fully interfertile, completely able to interbreed... Of course, like so many sweeping statements, no one has carefully tested this for all possible combinations.

It is true that research has not answered this question, but a recent study tell us that some combinations seem as fertile as same-race couplings. I can't access the full text, but here's some of the abstract:

This study uses 2000 - 2005 American Community Survey data on married (n =272,336) and cohabiting (n = 48,769) couples to compare the fertility of endogamous and exogamous couples. Interracial and interethnic partnering do not affect fertility for cohabiting, Black-White, Mexican-White, and Puerto Rican-White intermarried couples, but it does reduce fertility in Chinese-White and Asian Indian-White intermarriages (Fu, Vincent Kang. Journal of Marriage and Family, Volume 70, Number 3, August 2008 , pp. 783-795(13)).

Wouldn't you assume that if there's a biological reason for low fertility in some inter-ethnic pairings, it would more likely to show up in black/non-black couples than in other crossings. The black/non-black split is older than any of these other splits, isn't it?

So it seems as if humans are fully inter-fertile (though we might want to look at Aborigines and Bushmen to make sure).

Life is pretty flexible. It has to be, by definition, or it becomes non-life. We don't see what can't exist, so we should not be surprised when what does exist is good at existing and perpetuating itself despite obstacles. "Life... finds a way." There's even reasonable speculation that human/chimp crossovers are possible with little or no advanced genetic engineering. (Google "humanzee".) That may or may not be the case, but it puts interracial fertility into some perspective.

I'm not sure what counts as fertility, actually. I believe chihuahua sperm can fertilize mastiff ova, but the little fella probably wouldn't be able to pull off the courtship thing. And I'll bet a chihuahua dam couldn't bring a clutch of chihuahua-mastiff pups to term. If there were no other dog breeds, I'm not sure you could treat them as a single species: human intervention is the only way for them to interbreed.

Are Chinese-White mixes less fertile than both W-W and C-C pairings? Because East Asians have lower fertility. East Asian sperm, in particular, is genetically worse. (and lower estrogen, etc, in the females would reduce fertility as well)

Are Chinese-White mixes less fertile than both W-W and C-C pairings? Because East Asians have lower fertility. East Asian sperm, in particular, is genetically worse. (and lower estrogen, etc, in the females would reduce fertility as well)

i really doubt that this matters much. it isn't like you need to keep fucking someone after you impregnate them. old dudes with crappy sperm can have plenty of kids if they want to usually.

Just throwing it out there -- I suspect fertility quality does play a role in family size but can't say how much. I do agree with you though that A-W couples are exactly the kind of educated, upper-class folks who have smaller families.

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"I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind; it may be the beginning of knowledge, but you have scarcely, in your thoughts, advanced to the stage of science, whatever the matter may be." ~ Lord Kelvin